Effect of Annealing Temperature on Microstructure, Mechanical and Corrosion Properties of TiVNbZr0.5Hf0.5 Light-Weight Refractory High Entropy Alloy

This work aims to investigate the effect of annealing temperature on the microstructure, the mechanical and corrosion properties of TiVNbZr0.5Hf0.5 light-weight refractory high entropy alloys. The designed alloys were first produced by the vacuum arc melting route and then annealed at different temperatures (400°C, 500°C, and 600°C) for 24 hours under high-purity Ar gas flow. The results showed that the as-cast alloy exhibited a single disorder BCC structure. Meanwhile, besides the main disorder BCC phase, the C15 Laves phase has been detected for the alloys after annealing at different temperatures, confirmed by X-ray diffraction patterns and selected area diffraction patterns. The as-cast and annealed samples at 400°C show their excellent compressive ductility at room temperature. Annealing at 500°C and 600°C reduced compressive ductility due to the more introduction of C15 Laves phase precipitated in the interdendritic areas. Generally, the Vickers hardness and strength of RHEAs increased with annealing temperature. Additionally, outstanding corrosion resistance of the RHEAs was obtained in acidic media with even better performance by a simple annealing process at 400°C, 500°C, and 600°C.